well other than alpine/pioneer, you can go JVC, but that's kinda like a downgrade... although SQ is pretty nice from those decks, i'd rather get one of the new alpines with the 6ch digital time correction, mmmmm
but otherwise you could go with a higher end eclipse deck like the cd8443, and then get the commander advance so you can not only play mp3's, but you can also control the deck with voice commands, make cell phone calls through it, have GPS, and even roll down your windows via your voice... cool shiznit, and you can find a commander for under $200 US on ebay with GPS unit/antenna...
dunno how well the eclipse's do with mp3's but i'd check em' out...